Climate change and mental health: How extreme heat can affect mental illnesses

During heat waves, hospital admissions for mental health spike. The past 10 years were the hottest on recordand as we prepare for an additional scorcher of a summer, it’s time to take steps to extend our preparedness for extreme heat.

The potential for warmth stress, heat exhaustion and warmth stroke are well-known hazards of utmost heat. Yet, physical health just isn’t the one factor to contemplate under extreme heat; mental health may also suffer. Many people can relate to the sleepless nights during hot summer monthsin addition to anecdotal experiences of irritation and aggression when thermally uncomfortable.

But for those living with mental illnesses, the hazard of utmost heat is more dire than temperamental responses to day-to-day disruptions. From my research in Phoenix, Ariz. and the work of others through the 2021 heat dome in British Columbia, we all know that the warmth is exacerbating existing mental illnesses, increasing likelihoods of hospitalization and even death under warmer conditions for individuals with schizophrenia.

The interactions between environment and health are increasingly identified by researchers as public health concerns as air and water quality issues, in addition to death tolls from heatmake headlines. Research has shown that lower socioeconomic groups, racialized people and the unhousedare at greater risk of exposure to hotter conditions, while older adults are more vulnerable to hotter conditions.

Heat and mental illness

The relationship between mental illness and temperature has only recently been quantified as medical records and understanding of mental illnesses have improved. My work as an urban climatologist focuses on the impact of urbanization and warmth on human health. I explore the range of unexpected impacts of warmth on people. Specifically, I’ve studied the population diagnosed with schizophrenia.

Schizophrenia is a mental illness that disrupts transmission of knowledge to the brain. The a part of the brain most impacted also houses our thermoregulatory functions. It’s the part that tells us we’re too hot and to start out sweating or we’re too cold and will shiver to remain warm.

So those with schizophrenia aren’t able to reply to extreme heat the best way the final population does; their bodies aren’t telling them to take precautions. Further, the medications used to deal with schizophrenia also raise core body temperature. This implies that when taking the medication, individuals with schizophrenia are closer to the thresholds for warmth stress and stroke than the final population.

In studying hospitalizations for schizophrenia in Phoenix (where summertime overnight low temperatures are, on average, at 30 C) between 2006 and 2014, I discovered that minimum air temperature (the overnight low temperature) has a major relationship to the variety of hospitalizations for schizophrenia on that day and the next day. Around three per cent of all schizophrenia hospitalizations during that point period will be attributed to the overnight low temperature.

The risk is highest in each extremely cold (lower than 3 C) and intensely hot conditions (higher than 30 C). These hospitalizations cost the Phoenix health-care system over US$2 million (in 2024 USD). Certainly, Canadians see much colder conditions than 3 C at night but rarely experience overnight lows above 30 C; nonetheless, the 2021 heat dome resulted in over 600 deaths in B.C. and researchers found that schizophrenia was the chronic condition most related to risk of death through the extreme heat.

Extreme heat can have devastating impacts on those living with mental illness, our health-care system and our communities.

Schizophrenia just isn’t essentially the most common mental illness in Canada. However, it might serve for instance of how environmental issues can affect mental illness. One in every five Canadians experiences a mental illness annually. More than 250,000 Canadian youth experience major depression and systemic inequities exacerbated by disparities in treatment and take care of those experiencing mental illness.

While there are numerous various factors potentially contributing to mental illness, heat plays a pervasive role in a big selection of mental health issues. Taking what steps we are able to to scale back this burden on those living with mental illnesses may have knock-on advantages to the remainder of society, reminiscent of reduced use of hospital emergency departments during heat waves.

Coping with climate change

So if climate change is continuous to bring hotter summers, what will be done to forestall these hospitalizations and deaths? There are measures which have broader advantages along with improving mental illness outcomes during extreme heat.

A typical first step is ensuring access for all Canadians to air con. Statistics Canada highlighted the importance of air con for vulnerable populations. Warming conditions mean parts of Canada that didn’t need air con 30 years ago can now turn out to be oppressively hot inside buildings without proper cooling.

Yet, air con is depending on the electrical grid and continues to provide waste heat and greenhouse gas emissions. There is a greater way: designing our cities to be greener. There are lots of previously known advantages to greening cities; reducing the urban heat islandimproving air quality and in some cases increasing property values (each positive and negative outcomes).

However, there are some mental health advantages too. I contributed to a review of urban greenery mitigation science and highlighted the mental health advantages, including reduced depression, irritation and aggression.

Urban green space has been shown to enhance mood, self-esteem and even speed up recovery from illness. So because the temperature spikes and also you turn on the air con and reach for the cold drinks, remember there are impacts to us all beyond just physical health, and pause to notice how the warmth is influencing your mood.

Extreme heat will proceed to affect Canada (and increasingly so because the climate changes). However, the negative impacts on essentially the most vulnerable, including those living with mental illness can, partly, be reduced by taking steps to make sure our cities are benefiting us all.